For循環IF語句C編程

Question

char userChoice; 

printf("Choose how you would like to search.\nEnter A to display all players information.\ 
      \nEnter N to search a player based on name.\nEnter J to search a player based on jersey number.\ 
      \nEnter P to search a player based on position.\nEnter your choice: "); 
scanf("%c", &userChoice); 

do 
{ 
    if (userChoice == 'A' || userChoice == 'a') 
    { 
     for (index = 0; index < count; index = index + 1) 
     { 
      displayPlayers(&players[index]); 
     } 
    } 

    if (userChoice == 'J' || userChoice == 'j') 
    { 
     int jerseyNumber; 

     printf("\nEnter jersey number for the player: "); 
     scanf("%i", &jerseyNumber); 

     for (index = 0; index <= MAX_PLAYERS; index++) 
     { 
      if (jerseyNumber == players[index].jerseyNumber) 
      { 
       // If the condition is met the singleDisplay function is called. 
       // Containing the array of struct 
       singleDisplay(&players[index]); 

      } 
     } 
    } 
    if (userChoice == 'N' || userChoice == 'n') 
    { 
     char playerName[LEN_NAME + 1]; 

     printf("\nEnter name for the player: "); 
     scanf("%s", playerName); 

     for (index = 0; index <= MAX_PLAYERS; index++) 
     { 
      if (strcmp(playerName, players[index].firstName) == 0) 
      { 
       singleDisplay(&players[index]); 

      } 
     } 
    } 

大部分代碼僅適用於上下文，我遇到的問題是無法生成一個else語句，輸出一條消息給用戶，他們輸入的澤西島沒有找到。問題在於else語句在循環內部，並且無論多次打印它的消息，它都會比較數組中的所有數字。

Answer 1

您發佈的代碼的唯一相關的部分是：

for (index = 0; index <= MAX_PLAYERS; index++) 
    { 
     if (jerseyNumber == players[index].jerseyNumber) 
     { 
      singleDisplay(&players[index]); 
     } 
    } 

而且你的問題的唯一相關的部分是這樣的：

一條消息輸出給用戶一個else語句他們進入的球衣沒有找到。問題在於else語句在循環內部，並且無論多次打印它的消息，它都會比較數組中的所有數字。

好的，這很明確。你必須嘗試這樣的代碼（但未能將它展示給我們）：

for (index = 0; index <= MAX_PLAYERS; index++) 
    { 
     if (jerseyNumber == players[index].jerseyNumber) 
     { 
      singleDisplay(&players[index]); 
     } 
     else 
     { 
      printf("no match for jersey number\n"); 
     } 
    } 

當然，錯誤信息將被打印MAX_PLAYERS次，也許MAX_PLAYERS - 1時候，如果它被發現。所以，你需要修改代碼以明確地避免這種情況：

int found = 0; 
    for (index = 0; index <= MAX_PLAYERS; index++) 
    { 
     if (jerseyNumber == players[index].jerseyNumber) 
     { 
      singleDisplay(&players[index]); 
      found++; 
      break; 
     } 
    } 
    if (!found) 
    { 
     printf("no match for jersey number\n"); 
    } 

的break有可選的，但是是很好的形式，因爲它避免了一旦你已經找到了一個匹配檢查的詳細數字。也就是說，除非你想支持擁有相同球衣號碼的多名球員，在這種情況下，請刪除break。